N.Y. Comp. Codes R. & Regs. tit. 2 § 351.5
The rate of interest payable upon loans made pursuant to this section shall be one percent less than the valuation rate of interest adopted for the retirement systems. However, in no event shall such rate be less than the rate set forth in subdivision (c) of section 517 of the Retirement and Social Security Law, with respect to tier 3 members of the New York State and Local Employees' Retirement System, or the rate set forth in subdivision (c) of section 613 of the Retirement and Social Security Law, with respect to tier 4, 5 and 6 members of the New York State and Local Employees' Retirement System. Any change in the interest rate shall become effective on April 1st. However, the rate of interest applicable to any loan shall be fixed at the time the loan is made and shall not be affected by subsequent changes in the rate of interest applicable to new loans.
N.Y. Comp. Codes R. & Regs. Tit. 2 § 351.5